This invention relates in a general way to write and read control of data in a plurality of buffer queues. More particularly, the invention relates to write and read control of data in a plurality of buffer queues included in an asynchronous and possibly synchronous packet time-division switching system.
In such a switching system, buffer queues are respectively associated with outgoing time-division multiplexes. The incoming packets are memorized temporarily as they arrive in the queues associated with the outgoing multiplexes towards which the packets are to be transmitted. Write pointers respectively associated with the queues each indicate a first free cell in the corresponding queue. The queues are read cyclically under the control of a time base which successively selects the queues for reading and issues an incremented read pointer at the end of each queue read cycle.
The rate of incoming packets intended for a same queue is variable and the packets are written into the queue at almost random moments.
A buffer queue is dimensioned to absorb average fluctuations in the rate of incoming packets with regard to an average rate so that, as a rule, the filling level of the queues varies between a minimum level wherein the queue is empty and a maximum level wherein the queue is full but without reaching the maximum level. However, sporadic increases in the rate of incoming packets can be such that the filling level of the queue reaches the maximum level. All new writings of incoming packets in the full queue must then be inhibited while the queue is being emptied.